Black men in the United States bear a disproportionate burden of uncontrolled hypertension (HTN) when compared to other racial and ethnic groups. Black men are more likely to have HTN when compared to white men and their death rates from HTN are more than double those of white men. Effective antihypertensive medications are available to treat HTN but the rate of medication adherence is unacceptably low in black men. Previous studies of medication adherence in hypertensive blacks are limited in that they are cross-sectional and used self-report measures of adherence. The overall objective of this longitudinal study is to determine factors that are associated with poor medication adherence in black men with HTN. The factors to be investigated include self-efficacy, social networks, depression, physician trust, and masculinity. We propose to conduct a prospective study with 200 black men > 18 years with HTN and taking at least one antihypertensive medication followed in urban community-based primary care settings. Patients will be followed for 1 year. The primary outcome, medication adherence will be assessed with electronic monitoring and every 3 months post- baseline. Self-efficacy, social networks, depression, physician trust, and masculinity will be assessed using validated measures with face-to-face interviews every 3 months including at baseline. A secondary objective is to assess the impact of medication adherence on blood pressure. Results of this study will identify modifiable factors of adherence and lay the groundwork for tailored interventions to improve medication adherence among hypertensive black men.